1. Field of the Invention
The present invention relates to an apparatus for recognizing a lane along which a vehicle is traveling by processing an image of a road acquired via an imaging device, a vehicle thereof, and a program for causing a computer to perform processing of the apparatus.
2. Description of the Related Art
In recent years, there is known a technique of capturing images of a road along which a vehicle is traveling, detecting lane marks such as white and yellow lines on the road by processing acquired color images, and performing traveling controls of the vehicle and information presentation to a driver on the basis of the information on a lane (traffic lane), along which the vehicle is traveling, recognized as a result of the detection, with an imaging device such as a CCD camera mounted on the vehicle (for example, refer to Japanese Patent Laid-Open No. Hei 11-053691/1999).
In the lane recognition method described in the above official gazette, an edge histogram is derived by differentiating the density of all pixels of an image of a road ahead of a subject vehicle and calculating the sum of density derivatives at each pixel in the radial direction in a region around the focus of expansion. In this recognition method, the white and yellow lines on the road are recognized out of a plurality of candidate lines each having a peak density derivative in the edge histogram. More specifically, in the above recognition method, a candidate line having an extremely high peak value is determined to be a white line among the candidate lines selected from the edge histogram, and a candidate line including a strong R component, if any, is determined to be a yellow line on the road among the candidate lines superimposed on an image whose R component is enhanced.
In the recognition method described in the above official gazette, the white and yellow lines are detected as lane marks. Lane marks provided on the road, however, include those of various colors and types, in addition to linear lane marks such as traffic section lines (white and yellow lines). For example, there are used stud-type lane marks, which are provided discretely, such as Botts Dots and a cat's eye.
Moreover, the linear lane marks further include solid-line and broken-line lane marks. Further, for example, red color is sometimes used as a lane mark color in addition to the white and yellow colors. Since the lane marks of different colors or types have different meanings in the road rules in some cases, it is desirable to appropriately recognize the various lane mark colors or types in order to perform traveling controls of the vehicle and to present information to the driver.